Establishing an Operational Baseline for Severe Clear Air Turbulence Indices

Establishing an operational baseline for severe clear air turbulence indices

Since 2012 several enroute aircraft turbulence diagnostics have become available in the forecast displays used by meteorologists at NOAA’s Aviation Weather Center.  This research attempts to establish a baseline for severe turbulence forecasting by investigating various operational turbulence indices including Ellrod-Knox Index, Ellrod Index, and clear air turbulence diagnostics derived from the Short Range Ensemble Forecast.  Initial baseline thresholds for severe turbulence were established using select case studies of severe turbulence events.  Results reveal some correlation between severe turbulence PIREPs and baseline thresholds established from these indices; this could lead to providing additional lead time in SIGMET issuance before severe turbulence is encountered.  Future work on this includes collecting a larger sample of cases along with additional aircraft reports (PIREPs, in-situ turbulence reporting equipment, etc.) to further define thresholds.